Irreducible representation basis for unitary groups

A general method is presented for construction of a complete basis for finite-dimensional irreducible representations of those subgroups of the general linear group GLsub(n) for which irreps of GLsub(n) remain irreducible after the contraction from GLsub(n) to the subgroup in view. Using the constructed basis, the reduction coefficients for contraction of irreps of the group to those of its subgroups are calculated, as well as matrix elements for some physical operators